Saturday, February 9, 2013

Junk in the Trunk

I’ll start off with a few trunk facts that any self-proclaimed follower of Think Elephants International should already know. By definition, a trunk is the joint extension of an animal’s upper lip and nose. The elephant’s trunk is no exception.  It can hold up to 3.7 gallons (or 14 liters) at a time, allowing its owner to drink 10 gallons in a minute. Note, however, that the trunk is only a holding tank and not a direct avenue through to the esophagus. I imagine it’d be just as uncomfortable for elephants to drink through their trunks as it is for us humans to drink through our noses. Instead, water is simply sucked up into the trunk and then blown out directly into the mouth. Phuki is demonstrating the trunk-to-mouth maneuver below.

The anatomical structure of the elephant trunk claims somewhere in the neighborhood of 150,000 muscles and is completely void of bones. Similar muscle systems arranged along the dorsal, ventral, and both lateral sides of the trunk allow the elephant to flex their trunk in every direction by contracting key muscles along the corresponding side. In addition, radially arranged muscles grant the elephant control over the total volume available within their nasal passages, and presumably play a role in the production of certain vocalizations.

Elephants aren’t the only animals that have evolved a trunk, but they are certainly the largest living species to possess the unique appendage. It may be for this very reason that the elephant’s trunk is much longer than that of other trunked animals such as the tapirs. Whereas the trunk may have evolved for these smaller mammals to assist them in browsing for food, many speculate that, for elephants, the great length of the trunk provides an elegant solution to the problem that results when a tall animal needs to reach a water source at their feet.

Malayan Tapir

Of course the trunk isn’t the only solution to this problem that has been naturally selected across the animal kingdom. Consider the giraffe. Here’s a very tall animal that manages to quench its thirst via an incredibly long neck. Given the choice though (which of course we never are in the game of evolution), I would much rather have a trunk with two probing nostrils at the end than a two meter long neck with my head at the end. The benefits are the same. Just as the giraffe can grab a bite to eat from hard to reach heights, so can the elephant. But certainly it would seem favorable to keep your eyes and ears in a fixed position where they can be on alert if the potential for a predator encounter is high. I wouldn’t be very keen on drinking from a river if it meant I had to lower both my lips and my guard to the water’s surface.

Regardless of the how and why behind its evolution, the elephant trunk is certainly a spectacle. With so many adaptive features, it’s hard to imagine any animal turning their nose up at the idea of having such a versatile appendage.

That’s all for now… smell you later!